1. Field of the Invention
The present invention relates to a yaw-rate sensor and a method for operating a yaw-rate sensor.
2. Description of the Related Art
Yaw-rate sensors are known from the related art. For example, a yaw-rate sensor having two oscillating mass elements is known from the published international patent application document WO 03064975 A1. Micromechanical yaw-rate sensors for yaw rates about an axis which is parallel to the sensor plane (Z′ and yaw rate Qy) are normally designed as planarly oscillating masses or as masses rotating in the plane, which are subjected to a Coriolis force, which is perpendicular to the plane, when rotation occurs. This force is ascertained either via the electrostatic counterforce needed for position feedback regulation (closed-loop regulation) or, measured, for example, via the change in capacity due to the change in the distance to the substrate (open-loop operation). In addition to the setpoint measured variable, the Coriolis force, there are other forces that may act on the sensors and may induce a signal: linear acceleration and angular acceleration. The occurrence of these forces disadvantageously results in error signals during operation. With the aid of the differential evaluation of the forces which act on two masses moving in opposite directions, a distinction may be made between Coriolis force and the force due to linear acceleration (for example two masses oscillating toward each other or a mass rotating in a plane) for which the capacitance in two opposite positions is evaluated. Conventional sensors are insensitive to the angular acceleration about the y axis and also to the angular, acceleration about the z axis. Using conventional sensors, it is impossible to differentiate between Coriolis force and the force which arises due to the angular acceleration about the x axis. This limitation is extremely disadvantageous, since angular accelerations occur as interference variables.
It is therefore an object of the present invention to provide a yaw-rate sensor and a method for operating a yaw-rate sensor which do not have the disadvantages of the related art and are insensitive to angular accelerations.